1. Field of the Invention
The present invention generally relates to the field of manufacturing, and to the production of bent sheet metal components. More particularly, the present invention relates to an apparatus and method for integrating an intelligent manufacturing system, which manages and distributes design and manufacturing information throughout a production facility, with an expert planning system that generates a bending plan and control information for the production of sheet metal components.
2. Background Information
Traditionally, the production of bent sheet metal components involves a series of production and manufacturing stages. The first stage is a design stage during which a sheet metal part design is developed based on a customer's specifications. A customer will typically place an order for a particular sheet metal component to be produced at the facility. The customer's order will usually include the necessary product and design information so that the component may be manufactured at the facility. This information may include, for example, the geometric dimensions of the part, the material required for the part, special forming information, the batch size, the delivery date, etc.
During the design stage, a sheet metal part design may be developed by a design office at the manufacturing facility using an appropriate computer-aided design (CAD) system. Based on a customer's specifications, a two-dimensional (2-D) model of the sheet metal part may be developed by a programmer with a CAD system. Typically, a customer will provide a blueprint or drawings of the component and the critical geometric dimensions of the part. The drawings may also indicate any special forming or marking to be included in the part, as well as the location of holes or other types of openings on the surface(s) of the sheet metal part. The design programmer will often use this blueprint or drawing to develop a 2-D model on the CAD system. The 2-D model may include a flat view and one or more other perspective views of the sheet metal part, with bending line and/or dimensional information.
Before actual bending of the sheet metal component can take place, the part must first be punched and/or cut from initial sheet metal stock material. Computer numerical control (CNC) or numerical control (NC) systems are typically used to control and operate punch presses and/or plasma or laser cutting machinery to process the stock material. In order to facilitate processing of the stock material, a computer-aided manufacturing (CAM) system or CAD/CAM system can be used by a design programmer to generate control code based on the 2-D model. The control code may comprise a part program that is imported to and utilized by the punch press and/or cutting machinery to punch or cut the sheet metal component from the stock material.
The next stage in the production process is a bending plan stage. During this stage, a bending plan is developed by a bending operator at the shop floor. The operator will normally be provided with the blueprint or 2-D drawing of the component, along with one or more samples of the cut or punched stock material. With these materials, the bending operator will develop a bending plan which defines the tooling to be used and the sequence of bends to be performed. The bending workstation may include CNC metal bending machinery, such as a CNC press brake, that enables the operator to enter data and develop a bending code or program based on the bending plan.
Once the bending plan is developed, the operator will set up the workstation for initial testing of the bending sequence. During this testing stage, the punched or cut stock material will be manually loaded into the press brake and the press brake will be operated to execute the programmed sequence of bands on the workpiece. The operator will analyze the final bend sheet metal part and inspect it for conformance with the customer's specifications. Based on the results of the initial runs of the press brake, the operator may modify the bending sequence by editing the bending program. Further testing will typically be conducted until the bent sheet metal component is within the required design specifications.
One of the final stages in the production process is the bending stage. After the bending plan has been developed and tested, the bending operator will set up the required tooling at the bending station and operate the press brake based on the bending plan and the stored bending program or code. Job scheduling is also performed in order to ensure that the necessary amount of punched or cut stock material will be available on time at the bending station, and so that other jobs will be completed by the requested delivery dates. After the final bent sheet metal parts have been produced, the parts may then be assembled and packaged for shipping to the customer.
The conventional production and manufacturing process described above suffers from several drawbacks and disadvantages. For example, although the design and manufacturing data for each customer's order is normally archived physically (e.g., by paper in a file cabinet) or electronically (e.g., by storing on a disk or magnetic tape), such data are normally stored separately and not easily retrievable. Further, such data is often lost or damaged and valuable time is often lost in attempting to distribute the design and manufacturing information to the shop floor and to the other locations throughout the production facility. Considerable manufacturing time is also lost during the development of the sheet metal part design and bending plan, since the development of the part design and bending plan is primarily performed by the design programmer and the bending operator, and relies heavily on the individual's knowledge, skill and experience.
In recent years, there have been developments and attempts to improve the conventional sheet metal manufacturing process and to improve the efficiency of the overall process. For example, the use and development of 2-D and three-dimensional (3-D) modeling in commercially available CAD/CAM systems has facilitated and improved the production process and the modeling of bent sheet metal components. The 2-D and 3-D representations of the part may now be utilized by the design programmer and operator to better understand the geometry of the part and to more efficiently develop a part design and bending code sequence. The ability to store and transfer data electronically has also improved the flow of information from the design office to locations on the shop floor. With the advancement of computers and data communication networks, it is no longer necessary to search through a cabinet or file of old paper tapes or magnetic disks.
Other recent developments have also improved the efficiency of the design and manufacturing process, and have provided a greater level of automation in the production process of sheet metal components. For example, robotic manipulators and controllers have been developed for handling and positioning sheet metal workpieces within a press brake to perform bending operations. Further, material handlers have been provided for loading and positioning workpieces at a location for a robot to grasp and for unloading finished workpieces. Repositioning grippers have also been introduced for holding a workpiece within a press brake while a robot changes or repositions its grasp of the workpiece.
For example, a conventional bending workstation 110 for bending a sheet metal part (workpiece) 116 under the control of a manually created program downloaded to various control devices is illustrated in FIG. 1. The exemplary bending workstation 110 of FIG. 1 may comprise a BM100 Amada workstation, available from Amada America, Inc. (previously operating under the corporate name of U.S. Amada Ltd.), Buena Park, Calif. As shown in FIG. 1, the bending workstation 110 includes: a press brake 129 for bending workpiece 116; a five degree-of-freedom (5 DOF) robotic manipulator (robot) 112 for handling and positioning workpiece 116 within press brake 129; a material loader/unloader (L/UL) 130 for loading and positioning a blank workpiece at a location for robot 112 to grab, and for unloading finished workpieces; and a repositioning gripper 132 for holding workpiece 116 while robot 112 changes its grasp.
As further shown in FIG. 1, press brake 129 includes at least one die 119 which is placed on a die rail 122, and at least one corresponding punch tool 118 which is held by a punch tool holder 120. Press brake 129 further includes a backgauge mechanism 124 and one or more bending stages (three bending stages are illustrated in the example of FIG. 1). In addition, robot arm 112 includes a robot arm gripper 114 which is used to grasp workpiece 116. Material loader/unloader 130 may include several suction cups 131 which create an upwardly directed suction force for lifting a sheet metal workpiece 116, thereby allowing L/UL 130 to pass workpiece 116 to gripper 114 of robot 112, and to subsequently retrieve a finished workpiece 116 from gripper 114 and unload the finished workpiece.
In operation, loader/unloader (L/UL) 130 lifts a blank workpiece 116 from a receptacle (not shown), and raises and moves workpiece 116 to a position to be grabbed by gripper 114 of robot 112. Robot 112 then maneuvers itself to a position corresponding to a particular bending stage located within bending workstation 110. As shown in FIG. 1, stage 1 comprises the stage at the leftmost portion of press brake 129, stage 2 is located to the right of stage 1 along die rail 122, and stage 3 is located to the right of stage 1 in the drawing. If, for example, a bend is to be made at stage 1, robot 112 will move workpiece 116 to stage 1 and maneuver workpiece 116 within press brake 129, at a location between punch tool 118 and die 119, until it reaches and touches a backstop portion of backgauge mechanism 124. With the aid of backgauge mechanism 124, the position of workpiece 116 is adjusted by robot arm 112. Then, a bend operation is performed on workpiece 116 at stage 1 by moving die rail 122 upward. As punch tool 118 and die 119 simultaneously contact workpiece 116, so that workpiece 116 assumes a relatively stable position within press brake 129, gripper 114 may release its grasp on workpiece 116 to move gripper 114 away from workpiece 116. Press brake 129 will then complete its bending of workpiece 116, by completing the upward movement of die 119 until the proper bend has been formed.
Depending upon the next bend to be performed, and the configuration of workpiece 116, the gripping position of gripper 114 may need to be repositioned. Repositioning gripper 132, shown in FIG. 1, is provided for this purpose. Before performing the next bend, for which repositioning of robot gripper 114 is needed, workpiece 116 will be moved by robot 112 to repositioning gripper 132. Repositioning gripper 132 will then grasp workpiece 116 so that robot gripper 114 can regrip workpiece 116 at a location appropriate for the next bend or sequence of bends.
The bending workstation 110 illustrated in FIG. 1 is controlled by several control devices which are housed separately, including an MM20-CAPS interface 140, a press brake controller 142, a robot controller 144, and a load/unload unit controller 146. Press brake controller 142 comprises an NC9R press brake controller, and robot controller 144 comprises a 25B robot controller, which are each available from Amada America. Each of press brake controller 142 and robot controller 144 have their own CPU and programming environments. Load/unload unit controller 146 comprises a stand alone Programmable Logic Controller (PLC), and is wired to respective consoles provided for press brake controller 142 and robot controller 144.
Each of controllers 142, 144, and 146 has a different style bus, architecture, and manufacturer. They are coordinated primarily by parallel I/O signals. Serial interfaces are provided for transporting bending and robot programs to the controllers, each of which is programmed in a different manner. For example, logic diagrams are used to program the PLC of the load/unload controller 146, and RML is used to program robot controller 144.
In order to generate a plan for bending workstation 110, an operator must determine the proper bend sequence, tooling selection and tool stage layout, and the required robot motion and gripper repositioning. After determining the plan, supplied programs or software 148, such as an NC9R press brake program and a 25B RML robot program, may be developed by the operator for the various controllers. Each of these programs may be created with the use of an initial part design created from a CAD system. Both the robot program and the bending program must be developed manually, and are quite labor-intensive. In addition, design programmers often examine each part style to determine if previously developed and classified programs may be used or whether a new program must be written. However, since each classified program typically supports only a narrow range of acceptable part dimensions, new programs must frequently be written by the operators. The final RML robot program, when complete, is compiled and downloaded by the MM20-CAPS system 140 to robot controller 144. The bending program may be entered and debugged on a control pendant provided on press brake controller 142.
In view of the drawbacks of such systems, research and development has taken place in the field of intelligent/expert systems for automatically generating a bending plan and other manufacturing information required to produce sheet metal components. For example, U.S. patent application Ser. No. 08/386,369, entitled "Intelligent System For Generating and Executing A Sheet Metal Bending Plan", discloses an intelligent, automated bending system which generates a bending plan and then executes the generated plan to produce a bent sheet metal component. The system disclosed therein includes one or more expert modules or subsystems for providing expert information regarding tooling, holding and robot motion to a bend sequence planner, which determines and generates a final bending plan. A sequencer is also provided for executing the final generated plan and for formulating and transmitting the appropriate commands to the various components within the bending workstation in order to produce the bent sheet metal components. Further, U.S. patent application Ser. No. 08/338,115, entitled "Method for Planning/Controlling Robot Motion" discloses an expert system for planning and controlling the motion of a robot in order to facilitate the production of sheet metal components. The system disclosed therein plans the motion of a robot within a space confined by obstacles, so that the robot can hold and maneuver a workpiece throughout a sequence of bending operations to be performed by a bending apparatus.
Other advancements have led to the improvement of the management and distribution of design and manufacturing information throughout a production facility. For example, U.S. patent application Ser. No. 08/690,084, which was filed based on the priority of U.S. Provisional Application No. 60/016,958, discloses an apparatus and method for improving the efficiency and organization of stored expert knowledge by logically storing both the design and manufacturing information related to sheet metal parts, so that they may be easily accessed or retrieved from any area within the production facility. According to one aspect, previous job data is stored at a central database or file server so that it may be accessed from any location within the factory, and a searching method or process is provided so that previous job information that is similar to or the same as a current job request may be located and retrieved. Various other features are also disclosed in U.S. patent application Ser. No. 08/690,084 to, for example, facilitate the development of a bending plan by human operators.
Despite such advancements, there is still a need to provide greater flexibility in the manufacturing process and to integrate the features of systems similar to that described above in order to accommodate various types of workstations and job requests. Thus, while robotic machinery and expert systems have led to greater automization in the production of sheet metal components, such components and systems have not been integrated with intelligent manufacturing systems that manage and distribute part information to workstations throughout a manufacturing facility. There is also a need for a system that provides expert knowledge and information for both robotic and human operated machinery. Such a system could increase productivity by enabling expert systems to be selectively accessed to provide assistance to human operators in selecting and determining, for example, tooling or an optimum bend sequence, when developing a bending plan. In addition, by providing greater flexibility and customization in such expert and intelligent manufacturing systems, a bending operator or programmer could adapt such systems for a wide variety of uses to accommodate different types of bending workstations and machinery.